Rectifying device



Sept. 5, 1933.

J. E, FOSTER RECT'IFYING DEVICE Original Filed Jan. 8, 1925 5 W M r z Q W y @d M @5. f ,wwkwr m umw.. f

Patented Sept. 5, 1933 nutren STATES RECTIFYING DEVICE Julius y E. Foster, Pittsburgh, Pa., assignor to Radio Corporation of America, a corporation or Delaware Griginal application January 8, 1925, Serial No. 1,182. Divided and this application September 20, 1929. Serial No. 393,970 A 4 Claims.

bodying a double Wave rectifying assembly wherel by proper and complete rectification of an alternating current may be eiected, to provide a source o f substantially constant direct currentA or direct current energy for the energization of acathode element in a S-element tube.

The feature of importance that is involved in the construction of that rectifier unit is that the iilamentary electrodes of a double-Wave rectifier must be properly arranged and separated, or isolated, to preventcurrent leakage between the active zones around those filaments, if proper rectilication of the alternating current is tok be vbtained, and vshort circuiting of the associated transformer is to be avoided.

Insofar as the teaching ofthe parent application. in that direction may be applicable to the invention disclosed herein, it is desired ythat such teaching be considered as apart of the present application. Y n Y Another object of my invention is to provide a rectiiier for effecting full waving rectication with a plurality ofrthermionic cathode laments and cooperating anode means to constitute two individual rectifying units, with the units so arranged as to prevent current leakage between the active zones or areas of therespective units and thereby to prevent short circuiting of a transformer or other source oi energy with which the rectier may be empioyed.

Recent developments in radio receiving equipment have been towards the elimination of the various storage and dry batteries heretofore used, in order that the usually available source of house-lighting current vmight be utilized for the energization of radio tubes and the operation of the receiving sets. In order to obtain a suitable supply of substantially direct current and direct current voltage, rectifying devices ofl diierent kinds .have been employed, utilizing the thermionic valve character of .a heated cathode and an associated anode. With the employment of 55 tvvoheated cathodes in the same envelope, how'- ever, or transmitting both Waves of an alternat- (Cl. Z50-275) ing current, certain structural problems are encountered which must be taken care of in order to `obtain satisfactory operation of the rectiner of. such type.

' Where two lamentary electrodes disposed in the same enclosing vessel are heated, the spaces or zones immediately surrounding `the filaments become electronically active due to the electronic emission of the heated iilaments. If the medium surrounding the laments is gaseous, it becomes ionized by the'electronic activity of the heated iilaments and establishes a current-conducting path between them. When the laments and the co-operating anode element are connected to an V external transformer to cause the filaments to alternately transmit current Waves to the anode element, diierences of potential are set up between the various elements,y and a short circuit condition may be established on the transformer to which the rectifier is connected unless the elements are properly disposed within the envelope to prevent such condition.

If both iilaments are to be disposed Within the same envelope, as is preferable for reasons of 0 economy `and for saving of space, it is essential to prevent the leakage of current between the elements within the envelope, or proper operation of the rectifying system will not be established and maintained, and a short-circuit condition will be established by such leakage.

In order to prevent current leakage between two cathodes, or the active spaces surrounding them,.the anode means should be disposed to isolate and coniine'the yactive spaces surrounding theisrespective cathodes, and thereby prevent leakage of current vbetween the cathodes or the active spaces surrounding them, and thus prevent; the possibility of a short circuit upon the transformer or source of alternating current with vwhich the rectiiier is to be used. i

The; usual construction of a radio tube involves a central shell or stem which serves both as an insulating stand or support for all of the elements of the tube as Well as an insulating gas or air- 10 proof wall through which the various elements may be electrically connected to external termi-1 nalsl tov permit of a connection to an external electrical circuit.

In the embodiment which isillustrated herein, the cathode filaments are spaced and isolated and separated from each other. The cathodes and anodes of the respective rectifying units are supported by and upon the center stem, and auxiliary means are provided in co-operation with the center stem to provide supports at such points ment of the elements of the tube and the manner in which it operates; y v

Fig. 2 is a front view, partially in elevation, and partially in section, of a tube embodying the features illustrated in Fig. 1; and

Fig. 3 is a diagram of a radio system in which several such tubes are employed.

As is illustrated in Fig. 1, a thermionic device comprises a closed glass vessel 2 divided into an operating compartment 3 and two rectifying compartments 4 and 5. The operating compartment is separated from the rectifying compartments by a glass partition 6 and the rectifying compartments are separated from each other by glass partition 7. The operating compartment 3 contains a filament or cathode 8, a grid 9 and a plate or anode 10. The rectifying compartment 4 contains a filament or cathode 12 and a plate or anode 13. The rectifying compartment 5 similarly contains a filament 14. The two plates 13 and 15 are supported upon conductors 16 and 17, extending through the partition 6. Between the outer ends of the conductors 16 and 17 is supported the lament 8 of the operating compartment. An external conductor 18 isconnected to the mid-point of the filament 8.

Energy for the tube is derived from an alternating current circuit 20 which may be the ordi- ,nary light or power circuit, usually available. A.

" transformer supplies energy to light the filaments 12 and 14 through two secondary windings 21 and 22. One terminal of each secondary winding is connected to points 23 and 24, respectively, on `the primary winding 25, spaced from a mid-point "26 which serves as an artificial neutral point for the tube in-put system. The external terminal of the filament 8 is connected to the neutral point 26 through an adjustable resistor 27.

The compartments 4 and 5, with the elements contained therein, function as current rectifiers and thus co-operate to supply unidirectional current to the cathode 8. When the point 23 is negative relative. to the neutral point 26 the compart- When the point 24 is "negative relative to the neutral point the compartment 5 transmits current to the filament 8. Thus the current impulses transmitted to the filament 8 constitute a continuous unidirectional current to heat the lament 8.

In Fig. 2 is illustrated a tube constructed to embody the elements schematically illustrated in theV tube of Fig. 1.

This tube comprises a substantially evacuated vg-glass envelope 30 embodying a main operating compartment and having its lower portion extending inwardly within it and terminating in a centralV reentrant portion or stem 31 having a press rising from its inner end. The lower porv v-ticn 32 of the envelope is slightly reduced in Iwidth and fits into a base 33 of insulating material by means of which the tube may be easily and safely handled without subjecting the glass envelope to excessive strain. The insulating base 1333 supports a plurality of metallic pins or prongs 34 by means of which the elements of the tube may be connected to external circuits in bayonet type joints.

The rectifying chambersV 4 and 5 may be manufactured as small separate units comprising a glass vessel containing a cathode and an anode insulatingly supported with respect to each other. The units may be supported upon the wall of the internal shell or stern 31 by fusing with a small, hot flame during manufacture before the main shell or vessel 30 is placed in position and exhausted. Y

The rectifier anodes 13 and 15 are connected to the lament 8 by two substantially rigid conductors 36 and 37, which are also securely and rigidly held in position by two supporting elements 38 and 39, anchored in the stem 31. The top of the filament 8 is supported by a top support 40 secured to a supporting conductor 41 that is also supported by the center stem 31.

The conductors 35 and 37 to the rectifier anodes are thus held in rigid position against vibration by reason of their two-point support between the insulating stem 31 and the insulating support of the respective rectifying units.

In 3 is illustrated a radio system in which several tubes are employed for detecting and amplifying electromagnetic impulses.

Radiated energy-is received by an antenna circuit including an antenna 100, the primary of a vario-coupler 101, a variable condenser 102 and a ground connection. The secondary circuit of the vario-coupler is connected through a grid-leak 103 to the grid 9, and through a regulating resistor 104 to the common terminal-of the filament 8 of a detector tube 110, similar to that illustrated in Fig. 2. The tube is provided with the two rectifying units, the filaments of which are energized from the secondary windings of a transformer 105 energized from an alternating current circuit 106. The common points of the filaments are connected to the mid-point of the transformer primary and one terminal of each secondary winding is connected to a tap on the primary, spaced from the mid-point.

In addition to the detector 110, three amplifiers 111, 112 and 113 are provided. The detector and the amplifiers are inductively connected through transformers 114, 115 and 116. The plates of detector 110 and of the amplifiers 111 and 112 are connected through the primaries of the transformers 114, 115 and 116, respectively, to a common conductor 11'?. rIhe plate of amplifier 113 is connected to conductor 117 through the electromagnet of the receiver or loud speaker set 118. The conductor 117 is connected to a lter 108 through a resistor 126. The secondary windings of the transformers 114, 115 and 116 are connected to the artificial neutral point of the transformer 105 and to the grids of the amplifiers 111, 112 and 113, respectively.

Energy for the plate circuits is derived through a transformer 119 provided with taps to which the secondary windings may be connected to impress diiferent voltages upon the'plate circuit. The tap connections are controlled by two arms 120 and 121 operated simultaneously in opposite directions by a handle 122.

By means of the arrangement shown, the different operating circuits may be readily and easily controlled.

The rectifier unit 107 comprises a closed vessel provided with two chambers 124 and 125, each containing a lament and a plate. The filaments are energized from the secondary windings of the transformer 119 and are at the same time connected to the voltage taps on the primary by means of the two arms 120 and 121. The plates of the rectifying unit are connected through a reactor 130, the mid-point of which is connected to the filter 108.

What I claim as new and desire to secure by United States LettersV Patent isz- 1. A thermionic device comprising a sealed main envelope having a re-entrant portion at one end thereof, a pair of sealed compartments independent of the main envelope and adjacent said re-entrant portion, a half-wave rectier disposed in each of said compartments, a supporting press mounted on said re-entrant portion and extending within the envelope, a plurality of electrodes mounted thereon and means for connecting the outputs of said rectiers to at least one of said electrodes for energizing the same. l

2. A thermionic device comprising a sealed bulb having a re-entrant portion at the bottom thereof, two sealed chambers contained within the sealed bulb and disposed on opposite sides of said re-entrant portion, a half-wave rectifier in each of said chambers, a press rising from said re-entrant portion and extending into said envelope, cooperating electrodes mounted on said press and connections between said rectiers and one of said electrodes whereby said rectiers energize said electrode.

3. Athermionic device comprising a sealed envelope having at one end a reentrant stem with a press on its inner end, two sealed chambers adjacent said stem and closed to the interior of said envelope, a cathode and anode mounted in eachv of said chambers to form a half wave rectier, a thermionic cathode with two terminals and a cooperating anode mounted on said press, and connections between the terminals of said thermionic cathode on said press and the corresponding anodes in said chambers whereby said rectifiers energize said thermionic cathode.

4. A combined rectier and amplifier tube comprising a sealed envelope provided with a reentrant stem and a press portion, cathode, grid and plate electrodes which constitute the amplifier elements mounted aboveand supported from the press, a pair of sealedv independent enclosures mounted adjacent said reentrant stem, cathode and anode electrodes mounted in each of said enclosures to constitute a pair of half wave rectiers, and connections between the rectier anode electrodesand the cathode of the amplifier for energizing the same.

JULIUS E. FOSTER. 

